Is there a way to write images from render process in batch mode
Think this is possible in current master now (brand new from early 2016 April ;) ).

Basically, if you run:

blender -b yourblend.blend -f 0 -- --cycles-resumable-num-chunks 24 --cycles-resumable-current-chunk 1


…you say Cycles to 'split' the render (its sampling actually) in 24 'chunks', and only render the first one.

Then you can use a script to keep that picture (by copying it e.g. to a new name), and render the second chunk, etc.

See also original commit log.